Automatic (light-sensitive) rear light?

[Fatal Swan]

I never normally ride at night (nor do I really want to) so completely inexperienced when it comes to lights... But lately I've been doing more (road) riding in the early evening and realised that I'd find it useful to have an 'emergency' rear light - partly in case I need to do a repair/puncture and end up home later than I thought, but also because a lot of the local roads are through heavily shaded woodland and I've felt a bit exposed riding these sections without a light, evening during daytime.

There seem to be lots of pretty good and cheap little LED lights that would do the trick for the 'out later than expected' scenario, but are there any of these that have a light-sensitive on/off function for the unexpected darkness on heavily shaded roads? I'd rather not load down a lightweight bike with a cumbersome/bulky light for that purpose, so ideally something dinky and unobtrusive if possible!

Cheers

 

[mattr]

TBH, most decent LED lights will run for 100+ hours on a pair of batteries, so i'd just switch it on and leave it on, rather than trusting a potentially unreliable sensor.

I mean, my heaviest training months, ever, would only basically cover one set of batteries...... (120+ hours training in 4 weeks)

A lot of testers also have permanent rear lights now for racing as well.

 

[legrandefromage]

Just try to avoid the strobing rear lights - they are a bit of a bugger for those following!

 

[BobCatMax]

you could probably wire a photo-electric cell into this?

http://www.ebay.co.uk/itm/Xeccon-Geinea ... 2057256337

 

[Fatal Swan]

Thanks for the replies so far! I guess an auto on/off may not really be the solution if there's nothing obvious already out there. As a weight weenie and not a night rider the better of the teeny LED ones appeal to me (http://www.chainreactioncycles.com/nite ... prod133459 and http://www.chainreactioncycles.com/tope ... -prod92008) but these either seem run on USB-charged batteries with relatively short runtime for 'always on' use, or they use coin batteries which have to be replaced (can be done cheaply I know, but still seems a bit of a waste). One of the things that turns me off the short runtime rechargeable ones is that they seem to have rubber band mounts which may be pretty flimsy/breakable with repeated removal and refitting according to the reviews, and I've already broken two similar Garmin mounts like that in the past.

Any advice on a happy medium? Or is there a lightweight rear light somewhere that has a proper mount and takes a rechargeable AAA, for example? Thanks

 

[FluffyChicken]

Re:

Problem with auto lights is cars have light, quite horrible bright led ones now. Negating the effect of any light sensor ;-)

Put a power socket near your bike so you just have to plug the rear light in still on the bike.

 

[02gf74]

I know what you nean about the rubber band mounts. I was sceptical but they seem to hold my led front lights without moveming and those are heavier than rear lamps for sure. Just make sure you have some spare and maybe carry one. Also tie the lamp as if the band snaos, you loose your lamp,a front lamp will be held by the power lead.

Re rear lamp, cheap 2 aaa led are fine, neednt worry about the longevity of the batteries, many hours especially on flash mode.

 

[davidj]

Re:

Lezyne Zecto auto light. Lightweight, USB charge, great battery life and bright. Switches off after 3 minutes of no movement and powers up as soon as it moves again.

Got mine from Evans cycles, http://www.evanscycles.com/lezyne-zecto ... t-EV212918. If you have Tesco club card points you can double them up to use at Evans.

Had mine a while and really pleased with it so far. If you don't want to use the sturdy rubber band it also has a clip.

 

[just jacques]

I've been using Cateye TL-570 front & rear for a few years, they have light & motion sensors & the lens is road legal reflector. They can be expensive, but bargains are out there if you search.

 

[BobCatMax]

I have zectos front and rear on my riad bike and theyre amazing. Nit enough to see by up front but definitely to be seen, very bright. I had no idea there was an auto version, that looks amazing!